Cylindrical foundation tube



Sept. 13, 1938. v KO YOKOYAMA ,9

CYLINDRICAL FOUNDATION TUBE Filed April 27, 1936 Y INVENTOR.

Patented Sept. 13, 1938 UNiTED STATES PATENT or ies 3 Claims.

My invention relates to improvements in a cylindrical foundation tube and has for its principal object to provide effective operations in sinking a caisson easily by its own weight without putting additional weight.

For a, more complete understanding of my invention, reference should now be had to the accompanying drawing, in which Fig. l is an elevation partly in section of a foundation embodying my invention; Fig. 2 is an elevation illustrating another modification of my invention; Fig. 3 is an end view of the arrangement shown in Fig. 2; Fig. 4 is a sectional elevation illustrating a bridge pier using the foundation tube shown in Figs. 2 and 3.

Referring more particularly to Fig. 1, l designates a hollow cylindrical foundation tube made of concrete or masonry work such as a brick cylinder. According to my invention, the tube has a water tube 2 embedded in the walls thereof which opens at outlets 4 into grooves 6 on the outside of the wall for spreading or spraying water as at 5 uniformly over the outer surface of the tube i. In sinking the tube I the soil at its bottom is excavated from the interior of the tube and water is sprayed as shown by the numeral 5 out of the grooves 6 through the water pipes 2 which are connected to a high pressure pump or water pressure main (not shown for simplicity sake). The sprayed water effects lubricating action and decreases the frictional resistance between the outside wall of the concrete tube and the soil, thereby facilitating easy sinking of the tube by its own weight without applying an additional sinking weight.

Figs. 2 and 3 show a modified form of Fig. 1 in which screw threads I are formed around the outside wall of the tube I. A similar screw thread running in an opposite direction to that of the screw thread I is formed on the inside wall of the tube 5. The arrows 9 and Ill of Fig. 3 illustrate the running directions of the outer and inner screw threads respectively. Water is sprayed around the outside wall of the tube I through the water pipe 2. In sinking the foundation tube of this form, the soil at bottom of the tube is removed from the interior of the tube as usual. Then the sinking of the tube l is further promoted by its own screw action due to its external screw thread 1. After the tube i has been sunk, the interior of the tube I is packed again with sand and gravel etc. up to a suitable depth so that the further screw motion may be prevented due to the internal screw thread 8. The bearing force for the tube is thus increased due to the increase of the projecting area of the inner and outer screw threads i and 8. The foundation of this kind is suitable for use with a comparatively soft soil. The internal screw thread 8 is not always necessary and any pro- 5 jection for preventing the screw motion of the tube may be substituted therefor.

Fig. 4 illustrates a bridge pier using the hollow cylindrical foundation as shown in Figs. 2 and 3. H designates the water level of a river 10 and I2 is the river bed. After the tube or caisson i is sunk to a suitable depth into the river bed l2 and the setting operation has been completed the interior of the foundation is packed again with soil l3 up to a suitable height. A base block M is provided in the caisson to increase the bearing pressure. The base block W is preferably provided with openings i5.

Though I have described in the foregoing several embodiments of my invention referring to the drawing, yet the cross-sectional shape of the foundation tube or caisson may be changed to any suitable form such as rectangle, square. polygon or ellipse. The foundation tube is preferably made of concrete, but it may be made of 2 masonry work in general including brick or stone work. The foundation of my invention may be applied to a foundation tube of comparatively large diameter and the present method is also applicable to a well sinking.

What I claim as new and desire to secure by Letters Patent of the United States, is:--

1. A cylindrical foundation tube made of concrete or masonry work comprising Water supply pipes embedded in the wall of said tube and grooves provided on the external wall of said tube for spreading water along the outer surface of said tube.

2. A foundation tube comprising means for flowing water along the outer surface of said tube, screw threads formed on the outer surface of said tube and means provided on the inner surface of said tube for preventing the further screwing motion of said tube after the same has been sunk into a desired depth and soil has been packed therein up to a desired height.

3. A cylindrical foundation tube made of concrete or masonry work having screw thread projections formed on the outer surface, and other screw thread projections in the opposite direction formed on the inner surface and means for flowing water along the outer surface of said tube.

KO 'YOKOYAMA. 

